My Leashed Dog Attacked An Unleashed Dog That Approached Us

I was out walking my 2yo labrador. Another unleashed labrador/pitbull approached us and my dog attacked him. He has never attacked any other dogs but for some reason he did today. My dog bit him and the other dog was bleeding. I managed to get my dog to let go after like 5-10 seconds of me beating the shit out of my dog. 15 minutes later i get a knock at my door and shes saying shes gona call the front office and try to get me evicted for having an aggressive dog. The thing is that dog was right infront of my house unleashed and when i opened the door he jogged to us ans i guess my dog tool that as a threat. Shes saying shes going to either evict me or get my dog put down. Does anyone here know if what she is saying is true or is she is in the wrong for having her dog loose?